Private wrote:
jaywitkow@yahoo.co.uk> wrote in message
news:1152226401.475838.3010@m73g2000cwd.googlegroups.com...
snip
when I stumbled across a 5500W Generac generator, like new, at a
pawn
stop for $389.99. It occurred to me that it would be nice to have a
standby generator for the house, so I bought it.

Then when I got it home I realized how extremely noisy it is. You
can
probably hear this thing about 1/4 mile away or more. It sounds at
least twice as loud as my Honda lawnmower. After a lot of research
on
sound control, I came up with a hole in the ground as the most
practical. I considered double 2x6s, by the way, but this would
require
snip

I bet if you route the exhaust through an old auto muffler (and the
longer
pipe you will need to get it out of any enclosure) that you will
notice a
big reduction in the sound level. Do not bother to disconnect the
original
small muffler. Make sure you use some kind of a rain hat.

I did quite a bit of research on the automobile muffler idea. The
consensus seems to be that automobile mufflers don't reduce the noise
much.

I've got an 8 hp woodsplitter with an automotive muffler and a VW beetle
chrome tip welded into the outlet. It makes virtually no exhaust noise.

I think it has a lot to do with the quality of the engine and the RPM.
Honda makes very quiet generators, for instance, but they cost about
$3000, I think. I only paid $390 at a pawnshop for mine. I actually
loaded the generator up one day and took it to 2 muffler shops. Both of
them told me they had done this before and it didn't help much.

Here's a quote from a generator thread:

"Now. Since I've already done what you're thinking about doing, some
comments. A lot of noise comes from the exhaust but nearly all of it.
My Generac with the super-quiet muffler is still noisy, far too noisy
to use in a CG.

Much of the noise comes from the intake roar. This is much more
problematic to silence, since there has to be an air cleaner in the
path and since the intake right up to the carb on the Generac is
plastic. I've experimented with a commercial air compressor
muffler/air cleaner with some results. This Speedaire unit, available
from Graingers, uses tuned tubes to cancel the steady drone of the air
compressor. The frequency of the generator is much higher, as it runs
much faster, so some trimming of the tuning tubes is necessary. I
haven't installed it on this generator because it is too small.
Probably OK for a 4 or 5 kw generator.

Other major sources of noise include the valve train, the cylinder fins
and the crankcase walls. I've applied liquid rubber such as used in
bed liners to the crankcase which helped some. Keeping the valve train
adjusted tight reduces the noise at the risk of a burnt valve. No
solution yet for the cylinder and head fins, which can't be coated."

Those are all sources of noise. If you want a truely quiet engine, get a
Mazda rotary.
The engine in my wood splitter is an old Wisconsin cast iron, flat head
dinosaur.
I have a generator with Honda OHV engine and it is much noisier than my wood
splitter, the loudest noise is the exhaust.
As far as intake noise, the air cleaner ass'y from a car will quiet an air
compressor or a small engine.

jaywitkow@yahoo.co.uk> wrote in message
news:1152233484.097491.132810@s13g2000cwa.googlegroups.com...

YouGoFirst wrote:
jaywitkow@yahoo.co.uk> wrote in message
news:1152156053.927529.55580@m79g2000cwm.googlegroups.com...
I have a portable gas generator that I want to drop into a hole in the
ground for use during power outages. I have already bought a 1-ton
trolley and a 1-ton hoist and I need to find an I-beam (or a T-Beam?)
for a 10-ft span to mount the trolley hoist on. The generator weighs
about 200 pounds and the hoist and trolley weigh maybe 50 pounds. It
would be nice to have a 2:1 safety margin. Or, in otherwords find an
I-beam that could handle a load of 500 pounds.

Not to spoil everybody's fun, but I just have to ask why do you want to have
a hoist system? The only reason that I would go with anything like that
would be if I had no friends, and lived 600 miles from anybody. With 3 more
people and some rope you could easily lower the generator into the pit.
Unless you have some reason to have a hoist permanently mounted above the
pit that you haven't explained.

I'm retired and most of my relatives have moved out of state or died
off. I do have 3 close- by, likely suspects that would help me.
However, one of them has a very bad back and is currently putting off
surgery. The other one has a bad back, but works as a roofer foreman
and ignores it so I could use him, but he travels out of town a lot on
his job. The other one is usually close by, but 200 pounds is a lot for
2 people to lift in and out of a hole and my back isn't all that great.
I don't want to leave the generator permanently in the hole, by the
way.

The hole requires a roof anyway. So, it didn't seem like that big of a
deal to add the hoist. Another nice thing about a hoist is that I can
experiment with depth vs sound attenuation quite easily. It's a
judgement call. Once you get sucked into trying to reduce the sound on
these very loud generators, you make a lot of judgement calls.

But I do agree with a previous poster, why would you put a generator into a
pit?

Noise reduction. The whole problem is noise reduction and holes are
relatively cheap compared to other options and I have a relatively
large yard, too large really. These things are unbelievably loud--I
would guess twice as loud as my Honda lawnmower.

Have you considered a small block wall around the generator to direct the sound upwards. (Look at
the various highway sound deflecting walls.) You can make a roof that is light weight (aluminum
sheet metal) and designed to slide or hinged open like a clam shell. With a small "shed" you would
not necessarily have to move the generator, but leave it in the "shed" and ready to run in an
emergency. The walls would only have to be slightly higher than the height of the generator meaning
a door may not be required - open the roof and step over the wall. The roof could have a padlock to
keep unwanted guests out of the "shed".

Jim Y

That was actually my first idea. In fact, I called a guy that builds
cinder block fences and had him give me a bid on a 7-foot high
enclosure with 1-foot blocks. I decided to go relatively high because
my subdivision is on a hill and the top of even a 7-foot wall would
actually be quite low compared to my next-door neighbors. In addition,
my neighbors have bi-level house like I do, which makes things even
worse. So, I wasn't completely confident with a cinder block wall and,
of course, I would need a door.

Filled cinder block, as I recall, reflects about 66% of the sound wave.
So, I wondered if the sound would be over the top of the wall with a
couple of bounces. In addition, cinder block's attentuation
characteristics vary with frequency. The STC at 31 Hz, for instance, is
only about 32, but it's 58 at 8Khz. The cost to build the shed (without
the roof) would have been somewhere between $2800 and $3500, depending
on how I did it.

My second idea was to forget the cinder block and build low walls, as
you suggested, but with sand bags. My intuition is that sand bags would
absorb the sound rather than reflect it like cinder block. One of the
problems I ran into with sand bags, though, is I couldn't find any
acoustic numbers for them--no STC, and no coefficients of absorption
or reflection, etc. Another problem is that they deteriorate quite
rapidly with UV rays, so a roof would be needed to protect them.

Actually, with almost every scenario I came up with, I found that I
needed a roof of some sort. So, once I arrived at that conclusion,
adding a hoist and putting the generator in a hole didn't seem like
that big of a step. Also, I figured that my approach had saved quite a
bit of money, so the cost of the trolley hoist seemed relatively small.
Just as an example, I got the generator at a pawn shop for $390, while
an equivalent Honda that is fairly quiet probably costs over $3000 and
they probably still make quite a bit of noise.

This whole problem with noise attentuation is a real mind bender. First
you look at one option, then another and another and another. Then you
start back tracking and looking at all the options again. My advice is
don't buy a generator unless you really need it. If you do happen to
buy one on an impulse like I did and you want to kill the noise, you
will be facing a lot of difficult choices.

jaywitkow@yahoo.co.uk> wrote in message
news:1152234216.801967.218570@k73g2000cwa.googlegroups.com...
Chas Hurst wrote:
jaywitkow@yahoo.co.uk> wrote in message
news:1152232188.834683.299530@m79g2000cwm.googlegroups.com...

Private wrote:
jaywitkow@yahoo.co.uk> wrote in message
news:1152226401.475838.3010@m73g2000cwd.googlegroups.com...
snip
when I stumbled across a 5500W Generac generator, like new, at a
pawn
stop for $389.99. It occurred to me that it would be nice to have a
standby generator for the house, so I bought it.

Then when I got it home I realized how extremely noisy it is. You
can
probably hear this thing about 1/4 mile away or more. It sounds at
least twice as loud as my Honda lawnmower. After a lot of research
on
sound control, I came up with a hole in the ground as the most
practical. I considered double 2x6s, by the way, but this would
require
snip

I bet if you route the exhaust through an old auto muffler (and the
longer
pipe you will need to get it out of any enclosure) that you will
notice a
big reduction in the sound level. Do not bother to disconnect the
original
small muffler. Make sure you use some kind of a rain hat.

I did quite a bit of research on the automobile muffler idea. The
consensus seems to be that automobile mufflers don't reduce the noise
much.

I've got an 8 hp woodsplitter with an automotive muffler and a VW beetle
chrome tip welded into the outlet. It makes virtually no exhaust noise.

I think it has a lot to do with the quality of the engine and the RPM.
Honda makes very quiet generators, for instance, but they cost about
$3000, I think. I only paid $390 at a pawnshop for mine. I actually
loaded the generator up one day and took it to 2 muffler shops. Both of
them told me they had done this before and it didn't help much.

Here's a quote from a generator thread:

"Now. Since I've already done what you're thinking about doing, some
comments. A lot of noise comes from the exhaust but nearly all of it.
My Generac with the super-quiet muffler is still noisy, far too noisy
to use in a CG.

Much of the noise comes from the intake roar. This is much more
problematic to silence, since there has to be an air cleaner in the
path and since the intake right up to the carb on the Generac is
plastic. I've experimented with a commercial air compressor
muffler/air cleaner with some results. This Speedaire unit, available
from Graingers, uses tuned tubes to cancel the steady drone of the air
compressor. The frequency of the generator is much higher, as it runs
much faster, so some trimming of the tuning tubes is necessary. I
haven't installed it on this generator because it is too small.
Probably OK for a 4 or 5 kw generator.

Other major sources of noise include the valve train, the cylinder fins
and the crankcase walls. I've applied liquid rubber such as used in
bed liners to the crankcase which helped some. Keeping the valve train
adjusted tight reduces the noise at the risk of a burnt valve. No
solution yet for the cylinder and head fins, which can't be coated."

Those are all sources of noise. If you want a truely quiet engine, get a
Mazda rotary.
The engine in my wood splitter is an old Wisconsin cast iron, flat head
dinosaur.
I have a generator with Honda OHV engine and it is much noisier than my wood
splitter, the loudest noise is the exhaust.
As far as intake noise, the air cleaner ass'y from a car will quiet an air
compressor or a small engine.

I've heard that the small, Honda generators (~2000 W) that people buy
to take camping are very quiet, but they are expensive. I'm not sure
how noisy the larger Honda generators are though (4000W - 8000W), I've
assumed they are relatively quiet, but haven't heard anything about
them.

Actually, with almost every scenario I came up with, I found that I
needed a roof of some sort. So, once I arrived at that conclusion,
adding a hoist and putting the generator in a hole didn't seem like
that big of a step. Also, I figured that my approach had saved quite a
bit of money, so the cost of the trolley hoist seemed relatively small.
Just as an example, I got the generator at a pawn shop for $390, while
an equivalent Honda that is fairly quiet probably costs over $3000 and
they probably still make quite a bit of noise.

This whole problem with noise attentuation is a real mind bender. First
you look at one option, then another and another and another. Then you
start back tracking and looking at all the options again. My advice is
don't buy a generator unless you really need it. If you do happen to
buy one on an impulse like I did and you want to kill the noise, you
will be facing a lot of difficult choices.

You are over-analyzing this to an extreme degree. You know the
sandbags would not reflect sound nearly as much as a block wall, but
you eliminate that option because you can't find STC number? With that
logic you wouldn't have bought the generator in the first place. If
there aren't many power outages in your area, why go to all of this
trouble and expense. You've admitted that you bought something that is
not quite what you expected. Turn around and sell it - if it's in good
condition you might even make a profit.

If you're set on your course the (w)hole idea is asking for trouble on
many levels. Either have some fill delivered or berm up earth around
the generator location, have a drainage/ventilation pipe at the bottom
running to daylight, build a roof over the generator and line the
underside with sound absorbing material. It'll be used so rarely that
it won't cause a neighbor problem.

worse. So, I wasn't completely confident with a cinder block wall and,
of course, I would need a door.

Filled cinder block, as I recall, reflects about 66% of the sound wave.
So, I wondered if the sound would be over the top of the wall with a
couple of bounces. In addition, cinder block's attentuation
characteristics vary with frequency. The STC at 31 Hz, for instance, is
only about 32, but it's 58 at 8Khz. The cost to build the shed (without
the roof) would have been somewhere between $2800 and $3500, depending
on how I did it.

Use an ICF like www.polysteel.com and it will absorb a lot of sound.
While you don't need the insulating value, the project is then DIY and you
save money.

I have a portable gas generator that I want to drop into a hole in the
ground for use during power outages. I have already bought a 1-ton
trolley and a 1-ton hoist and I need to find an I-beam (or a T-Beam?)
for a 10-ft span to mount the trolley hoist on. The generator weighs
about 200 pounds and the hoist and trolley weigh maybe 50 pounds. It
would be nice to have a 2:1 safety margin. Or, in otherwords find an
I-beam that could handle a load of 500 pounds.

There's a scrap dealer about 50 miles from my house who says he has
lots of I-Beams to choose from. The question is, what do I look for? I
have no mechanical restrictions for the I-beam other than I would like
to have it light enough that 2 guys could lift it.

I know nothing at all about this sort of thing, but my intuition tells
me that almost any I-Beam that I'm likely to find would handle a load
of 250-500 pounds over a span of 10 feet. Is this true? Does anyone
have any advice to help me select an I-beam/T-beam?

Thanks in advance.

I was amused by the huge thread that you elicited - and you didn't
even get too badly bruised - only thing: nobody actually came out and
answered your question. Here it is. Using the section descriptions
used in the US, probably similar to the UK? you cannot use a c section
like
C3 X 4.1 (but that doesn't have the flange you need anyway)
It doesn't meet code in bending. Just in case, I'll mention the label
describes the depth times the weight per foot run.
You cannot use WT 2 X 6.5 It doesn't meet code also in bending.

You CAN use any I section more than 4 inches deep and 13 lbs/ft
like
W4 X 13 (safety factor of X12 for code requirement)
or a lighter section like
S3 X 5.7 (safety factor of X4 on code requirement) or bigger.

So find an I beam (not the right name but you know what I mean)
of 3 or 4 inches depth and weighing 6 lbs/ft on up and you are safe,
if your supports are at least pinned and 10 ft apart or less.

This whole problem with noise attentuation is a real mind bender. First
you look at one option, then another and another and another. Then you
start back tracking and looking at all the options again. My advice is
don't buy a generator unless you really need it. If you do happen to
buy one on an impulse like I did and you want to kill the noise, you
will be facing a lot of difficult choices.

It sounds like you should consider usage, how often are you planning on
firing the thing up? If you only are planning on running it once in a while
for maintenance, and when the power is out, I wouldn't worry about putting
it in a pit. Save your money and buy a power transfer switch and have that
installed into your house.

While creating a sound-proof enclosure would be nice, the majority of the
noise that you will be producing comes from the exhaust, so you may want to
look into directing the exhaust straight up.

I have a portable gas generator that I want to drop into a hole in the
ground for use during power outages. I have already bought a 1-ton
trolley and a 1-ton hoist and I need to find an I-beam (or a T-Beam?)
for a 10-ft span to mount the trolley hoist on. The generator weighs
about 200 pounds and the hoist and trolley weigh maybe 50 pounds. It
would be nice to have a 2:1 safety margin. Or, in otherwords find an
I-beam that could handle a load of 500 pounds.
There's a scrap dealer about 50 miles from my house who says he has
lots of I-Beams to choose from. The question is, what do I look for? I
have no mechanical restrictions for the I-beam other than I would like
to have it light enough that 2 guys could lift it.
I know nothing at all about this sort of thing, but my intuition tells
me that almost any I-Beam that I'm likely to find would handle a load
of 250-500 pounds over a span of 10 feet. Is this true? Does anyone
have any advice to help me select an I-beam/T-beam?

Having followed this thread so far, it strikes me that the approach should
be to get some experience actually using the generator before getting too
involved with holes for noise mitigation. I have a 6000W gasoline generator
that I use in my attached garage with the main door open. There are several
benefits to using a garage:
1. The generator stays dry.
2. The only neighbor who gets significant noise is the one directly across
the street from the open garage door (and only if his front windows are
open).
3. The generator is conveniently located for the twice-daily fill-ups needed
of the six-gallon gasoline tank. During rain or snow, I would not want the
generator outside in a hole. The longest power outage we ever had was
associated with a two-foot snowstorm.
4. The generator is close to the clothes dryer, so that a large cable can be
run from the 240V generator outlet to the 240V dryer outlet in order to
power the entire house. Most houses in the U.S. (I assume from your email
that you are in the U.K.) have 120/240V three-wire service with half the
120V service in the house on each side. (Of course, the house has to be
disconnected from the power company at the service main.)
5. The generator is conveniently located so that leftover gasoline can be
removed after each use, since it may be many months before the next use.
The above approach works fine for occasional outages. Mitigating noise is
nice, but it is not the only issue or even the main issue. (I say this as a
mechanical engineer specializing in acoustics.)

Actually, with almost every scenario I came up with, I found that I
needed a roof of some sort. So, once I arrived at that conclusion,
adding a hoist and putting the generator in a hole didn't seem like
that big of a step. Also, I figured that my approach had saved quite a
bit of money, so the cost of the trolley hoist seemed relatively small.
Just as an example, I got the generator at a pawn shop for $390, while
an equivalent Honda that is fairly quiet probably costs over $3000 and
they probably still make quite a bit of noise.

This whole problem with noise attentuation is a real mind bender. First
you look at one option, then another and another and another. Then you
start back tracking and looking at all the options again. My advice is
don't buy a generator unless you really need it. If you do happen to
buy one on an impulse like I did and you want to kill the noise, you
will be facing a lot of difficult choices.

You are over-analyzing this to an extreme degree. You know the
sandbags would not reflect sound nearly as much as a block wall, but
you eliminate that option because you can't find STC number? With that
logic you wouldn't have bought the generator in the first place. If
there aren't many power outages in your area, why go to all of this
trouble and expense. You've admitted that you bought something that is
not quite what you expected. Turn around and sell it - if it's in good
condition you might even make a profit.

If you're set on your course the (w)hole idea is asking for trouble on
many levels. Either have some fill delivered or berm up earth around
the generator location, have a drainage/ventilation pipe at the bottom
running to daylight, build a roof over the generator and line the
underside with sound absorbing material. It'll be used so rarely that
it won't cause a neighbor problem.

R

I like the berm idea that you mentioned, especially if it deflects the
water from the roof away from the hole. The actual noise sources from
the generator are only about 14 inches high. It could be that my
32-inch hole might wind up being only 1-foot deep with a 1-foot berm
around it. The bottom on the hole will be filled with at least 6-inches
of gravel, BTW. I plan on doing a lot of experimenting since I'm
retired and have the time and have already done most of the work.

The roof incidentally will set on top of a heavy-duty, used, walk-thru
scaffold that I got a good deal on. The whole thing is mostly hidden
from view from my house by a tree and it's hidden from the neighbors by
a 6-foot fence and my storage/hobby shed. I'm quite optimistic at this
point, but we'll have to see how it turns out. I've already painted the
scaffold the same color as my shed, incidentally, courtesy of 2 spray
cans of rustoleum--just for aesthetic purposes.

Having followed this thread so far, it strikes me that the approach should
be to get some experience actually using the generator before getting too
involved with holes for noise mitigation. I have a 6000W gasoline generator
that I use in my attached garage with the main door open. There are several
benefits to using a garage:

The approach works, and has a number of conveniences. However, you
do have to be VERY careful about CO production, even in an open garage
(check out/seal the penetrations between the garage and house, leave
as many doors open as possible).

During the great ice storm of 1998 up here there were a number of near
misses with CO poisoning even in open garages.

Secondly, using a suicide cord between a generator and dryer outlet
is a severe code no-no. While in certain emergencies (the power's
out, you have no time to buy sophisticated parts and wait for electricians,
and you only have limited options on installing a new genset)
it's the only way to go, but, it can be VERY dangerous on a number
of grounds. And highly unwise on a "planned installation" from
a legal perspective.

Here, you can get hit with a $6000 fine.

If you're planning out a "permanentish" installation, using a transfer
switch is the right way to go.

Short of that, extension cords to the equipment you need to power
is best.

Thirdly, security is important. People do strange things. Like
stealing generators from emergency services installations.
Chain it down!
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Actually, with almost every scenario I came up with, I found that I
needed a roof of some sort. So, once I arrived at that conclusion,
adding a hoist and putting the generator in a hole didn't seem like
that big of a step. Also, I figured that my approach had saved quite a
bit of money, so the cost of the trolley hoist seemed relatively small.
Just as an example, I got the generator at a pawn shop for $390, while
an equivalent Honda that is fairly quiet probably costs over $3000 and
they probably still make quite a bit of noise.

This whole problem with noise attentuation is a real mind bender. First
you look at one option, then another and another and another. Then you
start back tracking and looking at all the options again. My advice is
don't buy a generator unless you really need it. If you do happen to
buy one on an impulse like I did and you want to kill the noise, you
will be facing a lot of difficult choices.

You are over-analyzing this to an extreme degree. You know the
sandbags would not reflect sound nearly as much as a block wall, but
you eliminate that option because you can't find STC number? With that
logic you wouldn't have bought the generator in the first place. If
there aren't many power outages in your area, why go to all of this
trouble and expense. You've admitted that you bought something that is
not quite what you expected. Turn around and sell it - if it's in good
condition you might even make a profit.

If you're set on your course the (w)hole idea is asking for trouble on
many levels. Either have some fill delivered or berm up earth around
the generator location, have a drainage/ventilation pipe at the bottom
running to daylight, build a roof over the generator and line the
underside with sound absorbing material. It'll be used so rarely that
it won't cause a neighbor problem.

R

I like the berm idea that you mentioned, especially if it deflects the
water from the roof away from the hole. The actual noise sources from
the generator are only about 14 inches high. It could be that my
32-inch hole might wind up being only 1-foot deep with a 1-foot berm
around it. The bottom on the hole will be filled with at least 6-inches
of gravel, BTW. I plan on doing a lot of experimenting since I'm
retired and have the time and have already done most of the work.

The roof incidentally will set on top of a heavy-duty, used, walk-thru
scaffold that I got a good deal on. The whole thing is mostly hidden
from view from my house by a tree and it's hidden from the neighbors by
a 6-foot fence and my storage/hobby shed. I'm quite optimistic at this
point, but we'll have to see how it turns out. I've already painted the
scaffold the same color as my shed, incidentally, courtesy of 2 spray
cans of rustoleum--just for aesthetic purposes.

Since you are retired and like to mess around, do the berm thing, and

landscape it with a waterfall and plants and a pond :)

The hole in the ground is a nuissance for your back, and it will get
flooded in severe rainstorms which could fowl up your plans when the
power goes out. And in winter a hole is not a good idea (if you are in a
northern area).

"Now. Since I've already done what you're thinking about doing, some
comments. A lot of noise comes from the exhaust but nearly all of it.
My Generac with the super-quiet muffler is still noisy, far too noisy
to use in a CG.

Much of the noise comes from the intake roar. This is much more
problematic to silence, since there has to be an air cleaner in the
path and since the intake right up to the carb on the Generac is
plastic. I've experimented with a commercial air compressor
muffler/air cleaner with some results. This Speedaire unit, available
from Graingers, uses tuned tubes to cancel the steady drone of the air
compressor. The frequency of the generator is much higher, as it runs
much faster, so some trimming of the tuning tubes is necessary. I
haven't installed it on this generator because it is too small.
Probably OK for a 4 or 5 kw generator.

Other major sources of noise include the valve train, the cylinder
fins and the crankcase walls. I've applied liquid rubber such as used
in bed liners to the crankcase which helped some. Keeping the valve
train adjusted tight reduces the noise at the risk of a burnt valve.
No solution yet for the cylinder and head fins, which can't be
coated."

True, to get a quiet engine you need to deal with the loudest noise
source (in turn). For your installation, try using an autmotive muffler
on the intake.

One minute's study of the relative complexity of a car's intake and
exhaust systems will demonstrate that intake systems are much easier to
quieten than exhaust systems.

The other noise source that has not been mentioned is noise radiated
from the block itself. There is no easy solution to that, building a
heavy box around the engine, or burying it, are certainly reasonable
approaches.

He sure is.
You are throwing a lot of good money at a mistake.
Get rid of that loud generator.
By the time he is done, he will have spent more money than if he had sold
the generator and bought a Honda.
--
JerryD(upstateNY)